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Positive Phase 1b/2 Results from Ongoing REC-4881 TUPELO Trial Demonstrate Rapid and Durable Reductions in Polyp Burden in Familial Adenomatous Polyposis (FAP) at 25 Weeks
REC-4881 (4 mg QD) achieved rapid clinical activity, with 75% of evaluable patients showing reductions in total polyp burden and a 43% median reduction after
About this update from Recursion Pharmaceuticals, Inc.
[{"type":"text","content":"REC-4881 (4 mg QD) achieved rapid clinical activity, with 75% of evaluable patients showing reductions in total polyp burden and a 43% median reduction after 12 weeks of treatment (n=12)After 12 weeks off therapy (week 25 of the study), 82% of evaluable patients (9 of 11) maintained a durable reduction in total polyp burden, with a 53% median reduction observed from baselineNatural history analysis showed that 87% of untreated FAP patients - who resembled the inclusion criteria of TUPELO - had annualized polyp-burden increase, 10% remained stable, and 3% showed modest decrease—underscoring the disease’s progressive trajectory (n=55)40% of patients (4 out of 10) achieved a ≥1-point improvement in Spigelman stage—a clinically meaningful measure of upper GI disease severity to assess surveillance and clinical managementREC-4881 (4 mg QD) has a safety profile consistent with MEK1/2 inhibition, with the majority of treatment-related adverse events being Grade 1 or 2, Grade 3 events occurring in 15.8% of the safety-evaluable patients, and no Grade ≥4 TRAEs reported to dateFirst clinical validation of the Recursion OS, demonstrating how unbiased phenotypic and mechanistic insights—such as MEK1/2 rescue of APC loss-of-function—can translate to novel, differentiated therapeutics for diseases like FAP with no approved therapy and high prevalence of >50,000 patients in US and EU5Next steps: Engage the FDA in the 1H26 to define a potential registration pathway, and in parallel, expand the population from ≥55 to ≥18 years old, and further optimize dosing schedule SALT LAKE CITY, Dec. 08, 2025 (GLOBE NEWSWIRE) -- Recursion (Nasdaq: RXRX), a clinical-stage TechBio company decoding biology to radically improve lives, today announced positive Phase 1b/2 data from the ongoing TUPELO trial of REC-4881, an investigational allosteric MEK1/2 inhibitor for familial adenomatous polyposis (FAP). Through an unbiased phenotypic screen of thousands of compounds, the earliest version of the Recursion OS identified selective MEK1/2 inhibition as a highly specific mechanism capable of reversing APC loss-of-function signatures. Using high-content cellular phenomics driven by AI, REC-4881 emerged as one of the strongest phenotypic rescue hits, reverting APC-deficient cells toward a healthy state and suppressing ERK/MAPK hyperactivation downstream of APC loss. G...